The Invention relates to stimulation of wells penetrating subterranean formations. More particularly, it relates to the use of plate-like materials as proppants in hydraulic fracturing. Most particularly, it relates to the placement of materials such as mica as proppants in very low conductivity fractures.
Hydraulic fracturing remains a key method of reservoir stimulation, providing a significant increase in oil and gas production. Substantial efforts today focus on the design of well treatments, in particular fracturing and propped fracturing, in order to achieve and retain high fracture conductivity. There is such variety in reservoirs and formations being stimulated today that there is much room for special techniques for fracture stimulation. While numerous fluids and propping agents are now available, a number of issues associated with even modern materials limit their applications in many non-conventional reservoirs.
The traditional approach for high strength proppants is to create particles, which usually have a shape close to spherical, and to use a relatively uniform particle size distribution. The general assumption is that the particulate material will be randomly packed within the fracture. The spherical shape is relatively strong under anisotropic loading in such a random pack, and the narrow monodispersed particle distribution gives high conductivity. However, application of spherical shape proppants and sands in some cases is not preferable, due to insufficient crush resistance and/or to proppant embedment into the formation. Both of these factors decrease proppant pack conductivity, and both can be the consequence of the spherical shape. Furthermore, high strength proppants usually have a high specific gravity, which significantly decreases proppant transportability. For proper placement of heavy proppant, the use of highly viscous fluids is required, which impacts stimulation economics.
It would be advantageous to have proppants characterized at the same time by high crush resistance, low embedment, and high transportability.